Isolation of nonciliated bronchiolar epithelial (Clara) cells and alveolar type II cells from mouse lungs

A method is described for the isolation of alveolar type II cells and nonciliated bronchiolar epithelial (Clara) cells from mouse lungs. Following digestion of lung tissue with Sigma type I protease, viable cells were isolated to 65% purity for type II cells (6.4 +/- 1.5 X 10(5) cells/mouse) and 55-60% purity for Clara cells (2.6 +/- 0.9 X 10(5) cells/mouse). Viability, as assessed by trypan blue exclusion, was routinely greater than 90% in all enriched cell fractions. Although minor mitochondrial changes occurred during isolation, the morphology of the cells showed good preservation, as revealed by electron microscopy. The isolated cells were found to be metabolically active, as indicated by the presence of 7-ethoxycoumarin deethylase (a cytochrome P-450-mediated activity). The highest activity of this enzyme (278 +/- 116 pmol.min-1.mg protein-1) was found in the fraction enriched in Clara cells. The results indicate that this method produces viable cell populations that can be of value in investigations of the cellular distribution of lung metabolism activities.